With such a projection system, the advantage that the black level in the projected image (thus the residual brightness of a per se black image spot) can be clearly reduced compared with projection systems with only a single tilting mirror matrix is achieved through the optical series connection of two tilting mirror matrices.
However, it is very difficult to image the first tilting mirror matrix onto the second tilting mirror matrix by means of the imaging optics in high quality. In particular this is because, with tilting mirror matrices, the beam bundle of the reflected light used to generate images runs, not perpendicular to the modulator surface, but at an angle predetermined by the tilting position of the tilting mirror. A compact optical structure is also made difficult by this.